Simple Bench

the last of the larger live edge Mango pieces and legs of Monkeypod…the pins were turned from Milo, slightly darker than the Monkeypod but with a deep rich chocolate color and a wonderful nutmeg smell when working. The live edge theme is an interesting one…and I am struggling to find a balance, leaning too far towards rustic one moment and too modern the next…But perhaps this is why we work with wood, such a forgiving medium that truly appreciates our best intentions. As far as how to’s, it’s super straight forward…I have 3 pins on one end and 5 on the opposite, each pin has a slight shoulder which I think I would eliminate if done again…..17” tall, about 13” deep and just under 4’ long….

It is beautiful. And I hate to be the wet blanket but I have grave reservations about it’s stability/longevity. A four foot long bench supported by three skinny tenons which in turn are only supported by about an inch of end grain seems a like a failure waiting to happen. I’d add a stretcher system at the minimum. Just my .02

finish is straight forward, sealed with a two part epoxy and then spar….. my thoughts as to the leg attatchment was a result of the one narrow end on the top…trying to maintain as much long grain surface area as possible, increasing the shoulder area and keeping a substantial tenon.. The pins are apx 1 3/8” stepped to 1 1/8” diameter extending 1 1/2” into the legs and 2” into the seat. The holes or mortises were drilled 1 3/8” x 1/4” and then at 1 1/8” to depth….creating a shoulder… I would like to maintain the open space….perhaps 5 long spreaders postioned just above the floor…next one perhaps..thanks again

Thank you Dennis, I have always approached joints as surface area and grain direction…my hope in this case is I could satisfy the 2 requirements and still leave as much undisturbed /stable wood around the tenons…now I am second guessing myself somewhat…but…but…but..this surface area would still equate to a large square tenon…I have till Tuesday…perhaps drilling in 8 large screws through the pins…but then I would have to plug these holes….hmmm…....it is stout…short legs…racking shouldn’t be an issue…..if I were to reinforce the pins…I could turn exposed plugs that would appear to extend thru the legs…in hind site, I thought of this project as an epiphany..quick to build…layout was a snap….

The tenons won’t fail, the endgrain above the tenons in the end pieces will, at the top of the ends. Vertically. The only thing adding pins will do is to make a longer lever.

“this surface area would still equate to a large square tenon…” NO! Not in a Million. Draw a box around those three round “tenons” See the material between those three round tenons? Do you still want to stay with this statement? Now consider what the shoulder of an actual mortise and tenon joint contributes to the shear strength of a joint. The cheeks of the tenon acting on the face of the mortise. Another force resisting interface.

I really like this bench! I like live edge pieces. I like organic forms and composition and it really breaks my heart to be the one taking issue with your composition. But . . .

Take this mental test. Put the end with the three tenons on the floor. Now reach up, grab the end of the seat that’s four feet in the air and pull . . .where do you think it is most likely to break? Anyone who has ever hand chopped a mortise too close to the end of a piece will tell you . . .out the top of the end grain. Now imagine a couple of 12 year old cousins chasing each other around the house and suddenly somebody yells “settle down!” . The first slides to a stop on the bench, the next slides to a stop beside him with a quick hip check. Are they still above the floor? Or the mother-in-law comes over for a visit and , cane in hand, plops her well money’d, well fed, recent hip replacement and exhausted posterior on the thing . . .she plops down a bit less than in the strictly vertical plane . . .are you still in the will?

You get the point.

What if (on the next one) you extended the sides up six inches or whatever looks good to you and maybe rolled over the edge. A large hand shaped roundover, with a radius maybe twice or more the thickness of the material and recurving back on itself to keep with the live edge theme. The additional height would give additional tear-out strength to the top of the sockets while still keeping with the live edge theme. It would be sort of a wooden divan, a curved arm backless thingie. Just a thought. There are endless solutions to this challenge, with or without the round tenons. I’m sure many folks have an idea of what I should do with mine . . .

Grumpy…what a wonderful forum, sites such as this really are what the internet could or perhaps should be…ideas, thoughts and opinions being shared…You are right if the joint were to fail, it would fail in the legs above the tenons…..The lever length applying force upon this joint would be the leg length or the length of the top diveded in half, of course both legs could fail….I’m trying to think a sufficient shock at this point…off the top of my head…someone kicking one leg…..or perhaps someone sitting on the bench and another pushing that person….could cause the legs to fold in one direction or the other. Of course there could be a combination resulting over time…... I like you idea with the raised arms …somewhat of a live edge settee…...I am trying to think of a way that this could be achieved….to carve this effect…would require a very thick section of wood which would reqiure a great deal of hand work in each leg…but the even maintaing the scroll would look dramatic…the end or live ends would appear broken off…( I’m thinking about a carved from stone feel) ...For the bench above I like the surface plane, with the legs even with the top and it really is a stout little bench for it’s intended purpose…I ‘ll post a picture after I deliver it today…

A few years back FFW (i believe, my memory is horrible) had an excellent article on joints and failures…what I found interesting was the effect that the dovetail angle had upon the failure….anyhow I think of joints…regardless of style I view the tenon as a system to hold the shoulders secure..so in a round tenon I’m not thinking about how large a square will fit outside my diameter, but rather how long is the 160 degrees at the top and 160 bottom…and how much wood must be compressed/ sheared to cause the joint to fail..I’ll try and draw up a skecth to better explain my thoughts…not trying to convince anyone one way or the other, but rather just trying to be better understood.